Adui said:
Articifer; THANK YOU!! You have both given me advice I didn't know about and explained something to me I wondered about when I took it apart.
Remember I've NEVER dissembled this lock or even worked the screws in it in the 20-22 years I've owned the gun.
Both screws in the bridle were what I would call hand tight. I removed the bridle. free'd the main spring, and then I removed the screw that holds the tumbler to the hammer, it too was hand tight or more.
Now once I saw the sear was the culprit, I took it home, and removed the sear to examine the damage. The sear screw was what I would term ALMOST loose. By that I mean it wasn't wobbling loose but it took no real effort to turn the screw out.
At the time I figured the thing was just loose from never having been tightened over the years.. Now I wonder..
Bottom line, it just would cost too much to correctly "time" the sear screw so it can be tightened down snug and not bind the sear for a production gun. I have little doubt the way your sear screw was originally fit, it was a little loose for that reason and not because it loosened up over the years.
OK, other things to look for on a replacement sear and that is if it drags or binds on the lock plate on either side of the "bolster" or metal surrounding the area where the sear screw goes through the sear. Ideally, the sear should just contact the lock plate on the bottom of that bolster area and you should just be able to see a little light under the sear on each side of the bolster - but that is not how it sometimes works out. It is not extremely common where the sear drags on either side of the bolster, but it can happen.
What I like to do is take a good machinist's rule or something with a good FLAT edge and lay the bottom of the sear on it to see where the bottom of the sear contacts the flat edge. If you see light under the bolster area, then you will probably need to take a little metal off the front or back BOTTOM of the sear (or both) so the sear won't bind. I am only talking about taking off few thousandths of an inch, normally, but I've seen sears where more had to be taken off one or both sides of the bottom of the sear. BTW, you don't have to worry about going through the case hardening on either side of the bolster on the bottom of the sear, as long as you stay away from taking metal off the bottom of the bolster area on the sear, which will remain hardened and act as a bearing point.
I normally take the metal off the bottom of the sear where needed with either a medium India stone or even a carbide flat needle file, but you don't have to have either to do this. You can do it by wrapping a piece of 220 grit Emory Cloth (sandpaper for metal, but with a cloth back instead of a paper back - as sandpaper normally is sold) around a flat file and use that to "sand" off metal where you need it. The Emory Cloth can be coarser of finer than that, it just depends on how much you have to take off either or both sides of the bottom of the sear on each side of the bolster.
Once you have cleared metal off the bottom of the sear as necessary, you need to "break the edge" or remove any sharp edges or burrs from the bottom of the sear. Easy to do by "sanding" just a bit at an angle on the corners between the bottom and sides of the sear. I normally cold blue the area/s I remove metal from, but it is not absolutely necessary as long as you use a light coat of a good grade of gun oil to keep rust from forming.
Gus